Design Pattern: Abstract Factory 形式

Design Pattern: Abstract Factory 模式
在Abstract Factory模式中将具体的Product封装在具体Factory实现中，而客户仍只要面对Factory与Product的抽象介面，避免依赖于具体的Factory与Product，由于Factory封装了所必须的Product，所以要更换掉所有的元件，只要简单的抽换掉Factory就可以了，不用修改客户端的程式。

CustomDialog.java 
public class CustomDialog {    
private IButton button;    
private ITextField textField;        
public CustomDialog(IWidgetFactory widgetFactory) {        
setWidgetFactory(widgetFactory);    }        
// 由于客户端只依赖于抽象的工厂，工厂如何实作并无关客户端的事    
// 要抽换工厂并不需要改动客户端的程式    
public void setWidgetFactory(IWidgetFactory widgetFactory) {        
setButton(widgetFactory.getButton());        
setTextField(widgetFactory.getTextField());         
}    
public void layoutAllComponents() {        
// layout all components    }        
// 这边也是依赖抽象，实际改变了元件实例    
// 客户端代码也不用更改    
public void setButton(IButton button) {        
this.button = button;        
}        
public void setTextField(ITextField textField) {        
this.textField = textField;    
}        
public void showDialog() {        
this.paintDialog();        
button.paintButton();        
textField.paintTextField();    
}      
public void paintDialog() {        
System.out.println("custom dialog paints....");    
}} 

IButton.java 
public interface IButton {    
public void paintButton();
} 

ITextField.java 
public interface ITextField {    
public void paintTextField();
} 

IWidgetFactory.java 
public interface IWidgetFactory {    
public IButton getButton();    
public ITextField getTextField();
} 

MacButton.java 
public class MacButton implements IButton {    
public void paintButton() {        
System.out.println("Mac button paints....");    
}} 

WindowsButton.java 
public class WindowsButton implements IButton {    
public void paintButton() {        
System.out.println("Windows button paints....");    
}} 

MacTextField.java 
public class MacTextField implements ITextField {    
public void paintTextField() {        
System.out.println("Mac textField paints....");    
}} 

WindowsTextField.java 
public class WindowsTextField implements ITextField {    
public void paintTextField() {        
System.out.println("Windows textField paints....");    
}} 

MacWidgetFactory.java 
public class MacWidgetFactory implements IWidgetFactory {   
 public IButton getButton() {       
 return new MacButton();    
}        
public ITextField getTextField() {        
return new MacTextField();    
}} 

WindowsWidgetFactory.java 
public class WindowsWidgetFactory implements IWidgetFactory {    
public IButton getButton() {        
return new WindowsButton();    
}        
public ITextField getTextField() {        
return new WindowsTextField();    
}}